Method of treating casein threads, fibers, and the like



Patented jan. 30, 1 951 METHOD OF TREATING CASEIN THREADS, FIBERS, AND THE LIKE Leendert Maaskant, Arnhem, Netherlands, as-

signor to American Enka Corporation, Enka, N. 0., a corporation of Delaware No Drawing. Application July 14, 1947, Serial No. 760,936

7 Claims.

The present invention relates to the treatment of protein products, and more particularly to a method of improving the properties of threads, fibers and the like formed from proteins of either animal or vegetable origin.

Freshly spun protein threads, such as those produced from casein solutions, manufactured either by the dry spinning process, or by the wet spinning process which involves" coagulation in a spinbath containing acid and salt, possess no suitable textile properties until they have been given proper after-treatments. One such treatment is that of pie-hardening, usually with formaldehyde at normal or elevated temperatures. This pre-hardening treatment imparts to the thread a certain degree of resistance in water, and even in cold or heated alkaline solutions, which resistance is required for further trea ments.

The pre-hardening operation, however, is not sufficient to cause the threads to be resistant to dilute, hot acid media, such as are used during the dyeing operation. In these hot acid treatments, a large proportion of the protein is dissolved, and the thread becomes hard and brittle so that it is unfit for use as a textile product.

In order to render the thread useful for textile purposes, it must be subjected to a second treatment which renders it resistant to acid dye baths.

Such treatments have been performed with some degree of success, for example, by treating threads pre-hardened with formaldehyde, to a second operation consisting in subjecting the pre-hardened threads to the action of formaldehyde at elevated temperatures or after-heating the pro-hardened threads at temperatures ranging above, 100 C.

Other methods of improving the acid resistance of casein threads, are treating them with nitrite solutions (in the nature of desaminozation) or of treating them with solutions of the salts of trivalent metals, such as those of chromium, aluminum and iron. It has even been attempted to acetylate pro-hardened casein threads. In a rather recent development, casein threads have been treated with monoor di-alcohols of substituted phenols in order to increase their acid resistance.

Comparative experiments have proved however, that although these aftertreating operations have a favorable influence on the threads insofar as the decrease of solubility in hot dilute acid is effected, for example, when treated in acid dye baths of a strength of 1 gram of sulphuric acid per liter, the after-treatment is attended 2 by one or more disadvantages, such as decrease of the flexibility of the thread.

It has now been determined that the above mentioned advantage of greater resistance to dilute hot acid solutions, such as acid reacting dye baths, can be obtained Without the disadvantages normally flowing from the known aftertreatments. This novel treatment involves the use of pro-condensation products of resorcinol or a substituted resorcinol with aldehydes, preferably formaldehyde. These pre-ccndensation products are particularly useful when they are prepared in acid solutions, as in such a medium the pre-condensation stage can be maintained or retained during the time required for the treatment of the threads. The chemical structure of the pre-condensate in an acid solution renders it also suitable in other respects for treating casein fibers in order to obtain the required properties thereof.

Resorcinol and formaldehyde can be condensed in alkaline medium, but it is much more difficult to maintain the pre-condensate in the stage suitable for treatment for a sufiicient time, because when the condensation product is formed in the alkaline medium, it shows a tendency to continue its condensation. Moreover, the chemical structure of these rapidly changing pre-condensation products prepared in an alkaline medium is also dilferent.

In preparing the pre-condensation products in acid medium, resorcinol is introduced into an acid formalin solution and is immediately dissolved therein, after which the solution is heated. The solution is then cooled and diluted with water. Casein wool is introduced into this treatment liquid and allowed to remain therein for some time at room temperature. During this period, substantially all of the pre-condensation products present in the solution are absorbed by the casein fibers which have the property to absorb these pre-condensation products substantively. This is also the case with regard to coloring matter. This presents the advantage that during the heating period that follows, no agglomeration results. The casein fibers are finally removed from the bath, centrifuged, dried and heated for some time at 0. As a result of the foregoing treatment, no discoloration occurs.

It has also been determined that the finishing operation can be combined with this new method of after-hardening by adding the finishing agent, which must be acid resistant, to the diluted solution 'of pre-condensation products. Even if the thus treated final product is kept at boiling temw perature in an acid dye bath for an hour, only a small loss of portein occurs. When dyeing with acid dye baths of the normal acidity and at the normal temperatures, the loss of protein is even less. When a hot acid treatment is employed, the resistanceof the; casein thread, measured both wet and dry, has not substantially decreased, and the thread dyed in a hot bath retains its original flexibility and fullness of grip or hand. The treated textile material is also very durable with respect to the further customary operations performed thereon.

The excellent results attained by the foregoing treatment on casein threads were wholly unexpected because it has been determined that a corresponding treatment with pre-condensation products of phenol and formaldehyde, or urea and formaldehyde did not cause the thread to have the same properties and in particular the high resistance to hot acid dye baths. r In order to realize the best results by using the present process, it has been determined from the experiments that the following conditions should be met: the pre-condensate should be prepared at a pH-value less than 6 and preferably between 5 and 2.8; the proportion between resorcinol and formaldehyde should be in the ratio of at least 6 grammols of formaldehyde to 1 grammol of resorcinol.

Although some good effects are obtained in the first pre-condensation stage, i. e., as soon as the resorcinol and formaldehyde are mixed, the best pie-condensation stage is obtained by using a non-substituted resorcinol in the mixture which is subjected to a heating operation at 60 C. for one-half hour. As the temperature is increased the time of heating is correspondingly shortened, and the best temperature and time can be determined in special cases by carrying out parallel. experiments. When substituted resorcinols are employed, certain corrections are necessary connpared with the normal resorcinol, which corrections must be determined individually. Substituted resoreinols which are particularly suitable are 1.Cl.2.4.dihydroxyl:enzene, l.methoxy.2.4.dihy droxybenzene and 1.carboxy.2.4.dihydroxybenzone.

The following examples will serve to better illustrate the invention:

Example 1.A quantity of 0.5 kg. of resorcin'ol was dissolved in 3 liters of a 33% formalin solution and heated for one-half hour at 60 C. The pH-value was 3.5. water were add d. 10 kg. of dried casein fibers, pre-hardened with formaldehyde, were soaked in this pie-condensed resorcinol formaldehyde solution for one-half hour at room temperature, and were then removed by centrifuging, dried at 79 01 and heated for one-fourth hour at 105 C.

Example 2.The same conditions were maintained as in Example 1, except that 1.Cl.2.4.dihydroxvbenzene was substituted for resorcinol.

Example 3.A quantity of 0.5 kg. of resorcinol was dissolved in '6 liters of a 33% solution of formalin and the solution heated for one-half. hour at 60 C. The pH-value was established at 3.5. After cooling, 34 liters of water and 0.8 liters of a standard finishing solution were added. and well stirred. The aqueous standard finish ing emulsion contained, in addition to an emulsi-- fy'ing agent, 0.16 kg. of lanolin per liter, and. 0.3 kg. 01 parafiin oil per liter.

After cooling, 3'? liters of" 4 moved therefrom, centrifuged, dried and heated for a quarter of an hour at 105 C.

Example 4.When it is desired to incorporate the new hardening process directly into the continuous manufacturing process of the casein fibers, the following procedure can be followed:

Wet casein threads manufactured and prehardened in the normal way in the shape of a cable, are cut to staple, the bunches of staple fiber are opened and the fibers now having the shape of flocks, are spread on a conveying belt, conveying sieve, or moving wooden grate or like device, and transported. During their path of travel, after washing if required, they are treated with the diluted solution of the pre-condensates, for example, by a spraying operation. The required and proportionally calculated acid-resistant finishing agents can then be added to the diluted pro-condensation solution. The treatment of the lap (film) of flocks may take place in a counter-current manner so that the fresh pre-condensate solution is applied to the lap of flocks on the last point, for example, by spraying on the film of fibers, whereas the liquid used is collected and sprayed on the next to last point, etc. Finally, the substantially exhausted treat ment liquid, which is collected on the second or on the third point from the end, may still be :used to open the freshly cut cable outings.

In this way it is possible to use the property of the substantivity also in the continuous process to exhaust the pre-condensate solution.

The fibers covered with the pro-condensate and if desired with the finishing agent, are then to a great extent freed from liquid in a mechanical way, for example, by centrifuging, then dried on a belt at a moderate temperature, for ex ample, at C. and finally after-heated in the same continuous drying apparatus or in another constructed in the same way for about 15 minutes at 105 C.

Although the foregoing description has been devoted primarily to the aftertreatment and 10 kg. of pre-hardened and dried casein fibers were immersed in the treatment liquid for about one-half hour at room temperature, then res after-hardening of casein threads and casein fibers, other types of proteins may be treated 'in the same manner with the same beneficial results. Such threads or fibers may be either of animal origin, such as gelatin, or of vegetable origin, such as soy beans, peanuts, etc.

Reference is made to my co-pending companion application Serial No. 9,333, filed February 18, 1948, now Patent No. 2,519,842, dated August 22, 1950.

What is claimed is:

1. Synthetic casein threads, fibers, and the like which have been prehardened and there-'- after treated with acid solutions of pre-condensa' tion products of (a) formaldehyde and (b) a compound of the class consisting of resorcinol,

-chloro-, lower alkoxy-, and carboxy-substituted :resorcinols in the preparation of which at least .six mols of (a) per mol of (b) are employed, said casein products being characterized by such .a high resistance to hot dilute acid baths that substantially the entire casein content is retained in the products and their original flexibility and fullness of hand are substantially retained after treatment in said acid baths.

2. A process of increasing the resistance of pre-hardened threads, fibers, and the like of syn thetic casein origin to hot dilute acid dye baths Which comprises treating the products with an acid solution of precondensation products of o) formaldehyde and (b) a compound of the class consisting of resorcinol, chloro-, lower al koxy-, and carboXy-substituted resorcinols in the preparation of which at least six mols of (a) per mol of (b) areemployed, removing the thus treated products from the solution and centrifuging, drying and heating whereby when the products are subjected to subsequent treatments in hot dilute acid baths, their original flexibility and fullness of hand are substantially retained.

3. A process according to claim 2 wherein the pre-condensation products are of formaldehyde and rescrcinol.

4. A process according to claim 2 wherein the pie-condensation products are of formaldehyde and 1.Cl.2.4.dihydroxybenzene.

5. A process of increasing the resistance of pre-hardened threads, fibers and the like of synthetic casein origin to hot dilute acid dye baths which comprises soaking the products for about one-half hour in an aqueous solution having a pH value between 5 and 2.8 and containing precondensation products of (a) formaldehyde and (b) a compound of the class consisting of resorcinol, chloro-, lower alkoxy-, and carboxy-substituted resorcinols in the preparation of which at least six mols of (a) per mol of (b) are employed, removing th thus treated products from REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,693,926 Horsfall et al Dec. 4, 1928 2,103,138 Becker et a1. Dec. 21, 1937 2,211,961 Meigs Aug. 20, 1940 r 2,234,138 Kritchevsky Mar. 4, 1941 2,240,388 Calva Apr. 29, 1941 2,312,998 Kadt Mar. 2, 1943 Certificate of Correction Patent No. 2,539,958 January 30, 1951 LEENDERT MAASKANT It is hereby certified that error appears in the above numbered patent requlring correction as follows:

In the heading to the printed specification, line 8, following Serial No. 7 60,936 insert In the Netherlands, December '2, 1946 and that the said Letters Patent should be read as corrected above, so that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 17th day of April, A. D. 1951.

THOMAS F. MURPHY,

Assistant Gammz'ssz'oner of Patents. 

2. A PROCESS OF INCREASING THE RESISTANCE OF PRE-HARDENED THREADS, FIBERS, AND THE LIKE OF SYNTHETIC CASEIN ORIGIN TO HOT DILUTE ACID DYE BATHS WHICH COMPRISES TREATING THE PRODUCTS WITH AN ACID SOLUTION OF PRECONDENSATION PRODUCTS OF (A) FORMALDEHYDE AND (B) A COMPOUND OF THE CLASS CONSISTING OF RESORCINOL, CHLORO-, LOWER ALKOXY-, AND CARBOXY-SUBSTITUTED RESORCINOLS IN THE PREPARATION OF WHICH AT LEAST SIX MOLS OF (A) PER MOL OF (B) ARE EMPLOYED, REMOVING THE THUS TREATED PRODUCTS FROM THE SOLUTION AND CENTRIFUGING, DRYING AND HEATING WHEREBY WHEN THE PRODUCTS ARE SUBJECTED TO SUBSEQUENT TREATMENTS IN HOT DILUTE ACID BATHS, THEIR ORIGINAL FLEXIBILITY AND FULLNESS OF HAND ARE SUBSTANTIALLY RETAINED. 